Voltage regulator



Dec. 25, 1928.

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INVENTOR. I. 61 fioertis ATTORNEY Patented Dec. 25, 1928.

UNITE STATES PATENT OFFICE."

LELAN D C. ROBERTS, OF TOWACO, IN'EV JERSEY, ASSIGNOR TO AMERICAN TELEPHONE AND TELEGRAPH COMPANY, A CORPORATION OF NEW YORK.

VOLTAGE REGULATOR.

Application filed September 3, 1927. Serial No. 217,519.

.res'istances in series with the controlling resistance.

Since with the arrangement of the invention no set of relay contacts is required to carry more current than is suitable for the contacts of the ordinary fiat type relays, the arrangement has the advantage that it permits a considerable economy of construction without a sacrifice 0t efficiency.

The invention will be more clearly understood when the following detailed description of a desirable embodiment thereof is read with reference. to the accompanying drawing,

Figure 1 of the drawing shows diagrammatically the apparatus and circuit-connections of my novel regulator system.

Fig. 2 indicates, in a simplified and schematic form, the essential features of my regulator arrangement.

It is believed that the invention will be best understood if consideration is given first to Fig. 2 of the drawing. For the purpose of illustration, the generator is assumed to be one having a re'sistance, variable from 2.5 to 1.0 ohms, in series with the field. A voltmeter relay, shown in Fig. 1, causes the resistance inseries with the field of the generator to vary by actuating a relay train which shunts various resistances around a 2.5-ohm resistance which is permanently connected in the circuit. The desired regulation could be obtained by causing one or more of a group of 120 resistances to be shunted around this 2.5-ohm resistance. This would necessitate 120 relays. To save a portion of this expense, two banks of relays are provided, the A bank to give fine steps and the B bank to give coarse steps. The relays in the A bank are operated one by one until all are operated, if the voltage of'the battery is low. Then, the next nonoperated relay in the B bank is 0perated and all relays in the A bank released.

The voltage of the battery continuing-low, the

relays in the A bank are operated again successively and when all are operated, the next relay in the B bank is operated. In this way the resistance in series with the field is decreased until the voltageof the battery is restored to normal. Similarly,i'f the voltage of the battery is too high, the resistance in series with the field is increased by thesucc'essive release, one by one, of the relays in the A bank. When all are released, the relay in the B bankwhichwas last operated is released and all relays in the A bank 0 erated. If the battery-voltage continues hig 1, the A relays are releasedagain, one by one, and when all are released-another of the B relays is released. Means are provided as shown in Fig, 1, to move the A bank of relays from one step to another of the B bank.

Each resistance in the B bank is shown divided into two parts, one part consisting of 6 ohms and the other differing for each step. The reason for this is that the total resistance of the resistances in the A bank when they are connected in parallel is very nearly 6 ohms. This 6 ohms is in series with the residual resistance of the next coarse step to be operated. Therefore, when this operation takes place, the fixed 6-ohm resistance is switched in to take the place of the 6 ohms in A which is removed. Instead ofthese particular values of resistance which assume about 6 coarse steps and 20 fine steps, amore economical arrangement probably would be to have 12 coarse steps and 10 fine ones.

Consideration will now be given to the details of Fig. 1. A voltmeter relay, 4, is shown bridged across the battery whose voltage is to be regulated. Its armature is in series with a contact, 5, which is operated at any desired interval, say once a minute, by a clock mechanism or slow-operating relay chain. When it operates, if thevoltage of the battery is outside of the limits, the armature of the voltmeter relay will be making contact with one of the two contacts. Assuming that the voltage is too low, it will be touching the top contact. The battery connected through contact 5, will be impressed through a condenser in parallel with a high resistance on the winding of relayd, through contacts of relays a, b, and 0 in series, operating relay d. The object of the condenser shunted by a fixed resistance is to prevent more than one of the relays in the'dhain';ti to" t=from o'perating'a't one time. The resistance discharges the condenser when contact 5 opens; relay d Jocks up through its Lleftwontactandm. separate Winding. Its second-armature'fromitheleft prepares a circuit so that relay e will operate when the voltmeter relay neXt-touchos-its upper contact. The thirdarmature from the left connects the winding o'f relay c solidly to ground, preventing ,its release, by the opening ofthe common ground circuit through the operation of relay 29,- as explained herein below, before the release ofrelay d. The fourth armature inserts resistance 25 'in parallel with resistances 22-24 These four parallel resistances, which form four of the fine steps described above, arc,in series with resistance 20, bridgedacross-the fixed resistance21 which is 'in series; with the field circuit. Upon succeeding operations of contact 5, if the voltage remains low and, therefore, the armature of the voltmeter relaycontinues to touch the uppencontact, succeeding relays, e, f, g, etc. will be operated until finally t is operated. Upon the succeeding operation of 5-, .relay'6 will operate. Its :left armature removes the holding battery from all of the relays a to .t inclusive, releasing .these relays. The right-hand armature causes the operation of relay lOthroughga condenser bridged by a high resistance and through contacts of relayst', 8, and;9.. The object of the condenser is to prevent more than one of the relays 7 to 13"from operating at one time. The left armature of 10 bridges resistances l9 and '20 in series 'aroimd resistance 2-1. The second armature from the left disconnects resistances 22 to 27 from resistance20 andprepares a circuit so that upon-the operation of the relays at associated with -them they will be connected to resistance-v, which 'is one of the resistances in the coarse step controlled by rel-ay 111 The tlrird'armaturefrom the left of relay 10 conneotsjthe winding of relay'9 directly to ground, thus preventing an interruption of'the com-men ground circuit from releasing relay 9 until 10 hasjbee-n released. The fourth armature prepares a circuit sothat relay 11 will be operated the next "time relay =6 is operated-a$terall of the relays centrolling the fine steps have operated once more. The fifth armature locks 1'0 in the operating position.

If the voltage'oontinues low, the relays a to t, which control the finesteps, will operate once more in order, causing the operation of relay 11, which will insert another coarse step, and after that, relays 12 and 13 in order. If the battery voltage still remains too low, bell28 will ring, summoning an attendant.-

Now, assuming that the equipment is restored "to the original condition shown on .the drawing and that thebatteryvoitageincreases to the upper limit, the voltmeter relay armature will touch the lowertcon'tact, causing relay 29 to operate when relay 5 "next operates and thus disconnecting the ground from the windingtmfprelny 5a, releasing it. The conwinding and,therefore, decreasing the voltage of the generator. If the voltage contin- .ues'.h'igh, relaysc, b and a will be released upon successive operations of contact 5 and then relay 3 ,0 is released. The release of 30 causes .theoperation of 31 which connects 'hattery to relays-gr to 't' in turn, operating'them.

6 'is prevented from operating "because the lefitiarmature o f 31 opens its wmdin circuit. I Relay must 'r 'el'ea'se slowly .enoug fso that all relays, atoaf, willhave time to operate. If

this is not-easily done one relay, it isobv'iou's'ly easy 'to'do it byaJchainof 2 or 3 relays. The right contact of '30removes ,ground. from thewinding of relay 9, releasing it and removing resistances 17 and 18 from the parallel circuit shunted around 21. The functions of the other contacts of 9 have been described for 10 above. Y If'the voltage of the generator remains high, relays t to a will be resleased in succession again and cause the release of rela 8. Ifthe cycleis repeated again relay '7 wil be released .and after'that relay 33, causing be'll '32 to ring, summoning an attendant;

From theabove'description it is obvious that at .any time'a circuit is insuch condition that if thevoltagejof the ,generator increases or decreases beyond the allowable limits, a compensating change automatically takes place in 'theflresistance in series with the field Winding.

VVlii'le the invention has been specifically disclosed in one embodiment, which is deemed desirable, it is to be understood that it is capable of embodiment in other and different forms, within the true scope of the invention, as defined in the appended claims.

What is claimed is: s

'1. In association with a source of electric current having a resistance associated therewith and controlling the voltage thereof, a system for regulating the voltage of said source, said system comprising a voltmeter relay associated with the source, a resistance in shunt around said. voltage controlling resistance, circuit-making means responsive to .the oaeration of the voltmeter relay due 'to a de ciency' of the voltage of the source for decreasin said shunt resistance'by gradual steps until the level is restored, and circuit-breaking means responsive to the operation of the voltmeter relay due to an excess of the voltage of the source for increasing .said shunt resistance by gradual steps until the level is restored.

'2. In association with a source of electric current having a resistance associated therewith and controlling the voltage thereof, a system for regulating the voltage of said source, said system comprising a voltmeter relay associated with the source, a resistance in shunt around said voltage controlling resistance, circuit-making means responsive to the operation of the voltmeter relay due to a deficiency of the voltage of the source for decreasing said shunt resistance by gradual steps until the level is restored, circuitbreaking means responsive to the operation of the voltmeter relay due to an excess of the voltage of the source for increasing said shunt resistance by gradual steps until the level is restored, and means for giving an alarm if either the maximum increase or the maximum decrease of the shunt resistance fails to restore the voltage level.

3. In association with a source of electric current having a resistance associated therewith and controlling the voltage thereof, a system for regulating the voltage of said source, said system comprising a voltmeter relay associated with the source; a plurality of relatively small resistances: a plurality of relatively large resistances; means responsive to the operation of said voltmeter relay due to a. deficiency of the voltage of the source for connecting the large resistances successively in shunt around the voltage controlling resistance until the level is restored, then if the level is not restored, connecting one of the small resistances in parallel with the voltage controlling resistance and disconnecting the large resistances, and adding the large resistances successively to the shunt resistance, and repeating the operation until the level is restored; and means responsive to the operation of the voltmeter relay due to an excess of the voltage of the source for similarly increasing the resistance in shunt with the voltage controlling resistance by steps until the voltage level of the source is restored.

4. In association with a source of electric current having a resistance associated therewith and controlling the voltage thereof, a system for regulating the voltage of said source, said system comprising a voltmeter relay associated with the source; a plurality of relatively large resistances; a plurality of relatively small resistances; means responsive to the operation of said voltmeter relay due to a deficiency of the voltage of the source for connecting the large resistances successively in shunt around the voltage controlling resistance until the level is restored, then if the level is not restored. connecting one of the small resistances in shunt around the voltage controlling resistance and disconnecting the large resistances, and adding the large resistances successively to the shunt resistance, and repeating the operation until the level is restored, means responsive to the operation of the voltmeter relay due to an excess of the voltage of the source for similarly increasing the resistance in shunt with the voltage controlling resistance by steps until the voltage level of the source is restored, and means for giving an alarm if either the maximum increase or the maximum decrease of the shunt resistance fails to restore the voltage level.

In testimony whereof, I have signed my name to this specification this 2nd day of September, 1927.

' LELAND C. ROBERTS. 

